The invention generally relates to catheters which have inflatable balloon portions.
The invention more specifically relates to such catheters which can be inserted into and positioned by a bronchoscope.
The flexible fiberoptic bronchoscope is a triple lumen tube for containing an optic viewing fiber, a lighting passage and a suction channel. It allows both visualization of the tracheo-bronchial tree, through the viewing fiber, and sampling of secretions or tissue of the lung through the suction channel. The bronchoscope most commonly used to inspect the bronchial tree has a flexible tip which can be controlled so that inspections along branches with sharp bends may be followed more easily.
Flexible fiberoptic bronchoscopy is an invaluable tool for the diagnosis of many lung diseases. Two techniques involving the bronchoscope are bronchoalveolar lavage and tamponade of tracheo-bronchial bleeding, both of which are important in the diagnosis and management of respiratory diseases.
Bronchoalveolar lavage is the accepted technique of sampling the cellular content of the alveoli. This technique has greatly improved the understanding of many lung disorders.
In interstitial lung diseases, the cells seen in the lavage fluid represent the inflammatory and the immune effector-cell population present in the alveolar interstitium. This has allowed the characterization of different forms of "Alveolitis" and has opened a new frontier in the understanding of these disorders.
Bronchoalveolar lavage is also useful in diagnosing pulmonary infections (i.e.; pneumocystis carinii pneumonia, fungal infections, legionella, TB and CMV) and it has replaced open lung biopsy in the diagnosis of opportunistic infections in the immuno-compromised host.
Bronchoalveolar lavage is presently accomplished by wedging the tip of the flexible fiberoptic bronchoscope into a segmental bronchus. Then, injecting warm saline (37' C) through the suction channel of the bronchoscope to lavage the bronchus and alveoli. Effective retrieval of the saline lavage solution is a problem owing to the difficulties encountered in maintaining the wedge seal.
During this procedure, pressure must be applied to the bronchoscope to maintain an effective wedge seal. This pressure activates the cough reflex, disrupting the wedge seal, resulting in the leakage of the irrigating solution. Further, the applied pressure required to maintain the seal is occasionally traumatic to the bronchial mucosa.
Pulmonary hemorrhages are among the occasional complications of biopsy during bronchoscopy and can be life-threatening. During such hemorrhaging, the tip of the bronchoscope is wedged into the bronchus with the intent of limiting the bleeding to a small area of the lung. A serious inconvience of the present modality is that the tip of the bronchoscope is obscured by blood, and the lack of visualization does not allow for adequate assessment and management. After a seal has been made, vasoconstricting agents are instilled to control the hemorrhagic process. Normal saline is instilled and aspirated to wash the blood out.
The applied wedge pressure again creates patient discomfort, activates the cough reflex and disrupts the wedge seal, thus hindering the management of the hemorrhage.
To more easily study lung related diseases and to provide a less traumatic treatment, it would be desirable to be able to insert a balloon tipped catheter through the suction lumen of the bronchoscope into the bronchial tree, thereafter use the balloon, when inflated, to seal off a particular lung subsegment instead of applying traumatic pressure to the end of the bronchoscope. There is a problem, however, in inserting a balloon tipped catheter into the appropriate channel provided by the bronchoscope. The inside wall of this channel is articulated in order to provide the necessary flexible maneuverability while positioning the scope through the passages of the lung. The articulation generates ribbed walls that tear or otherwise damage the relatively delicate elastomeric material common to prior art balloon tipped catheters while it is being pushed passed such bends.
If a damaged balloon is later positioned and inflated in the bronchial tree of a patient, the balloon may rupture, thereby breaking the isolation seal of the particular subsegment under test or treatment and reducing the quantity and quality of the retrieved specimens. When detected, the damaged catheter must be removed and a new one inserted with the same problems caused by the ribbed walls of the bronchoscope.
Although some conventional balloon tipped catheters have recessed balloons, the balloon material of such catheters does not remain recessed if the catheter tube is curved sharply. It will overlap and create wrinkles or "bulges" on the inside of its curve and can be easily damaged by the ribbed walls of a bronchoscope. An example of such a catheter having a recessed balloon is shown in U.S. Pat. No. 3,734,100.
The principal object of the present invention is to provide a balloon tipped catheter which avoids the above-identified rupturing problems.
A more specific object of the present invention is to provide a balloon tipped catheter which can be inserted through a curved suction channel of a bronchoscope without damage to the catheter or balloon. The balloon can then be positioned and inflated at a predetermined location of a lung subsegment thereby creating an effective seal which will minimize or eliminate the cough reflex and much of the patient discomfort.